Will Google BAN without a reason?

Nowadays i see a lot of people who are saying that they had been banned by Google adsense...but why should a well reputated company like google ban a person?
They might have clicked on their own ads placed on their own website or something!i have been using Google adsense for past two years with NO PROBLEM and so many people do!
What do you think about this?DO YOU THINK THAT GOOGLE WILL BAN WITHOUT A REASON?